Cycloastragenol compounds belong to the lanostane tetracyclic triterpenoids in structure, and are indicant ingredient taxa in Astragalus plant. Cycloastragenol triterpenoid saponin ingredients, which are the main bioactive constituents of a common Chinese traditional medicine of Astragali (Astragalus membranaceus Bge.), have many pharmacological effects such as immunoregulation, cardiotonic effect, anti-ischemic injury in heart and brain, hepatic protection, anti-inflammation, anti-virus, kidney and pancreatic islet damage improving, and so on. Although the pharmacological effects of astragaloside ingredients has been affirmed, and the industrial production process of the total saponins and monomer saponin (astragaloside IV) are relatively mature (CN1172677C, CN 1543976A, CN 1189176C), this type of compounds are generally with the natures of poor solubibity and low bioavailability, which lead to hysteresis of the pharmaceutical research and limit their development and generalization as a medicine, so there is no product on the market as yet.
Cycloastragenol-6-O-β-D-glucoside (CMG) (Formula 1), the structure of which was first reported in 1983 by Isao Kitagawa et al. (Chem. Pharm. Bull. 31 (2) 698-708, 1983), was obtained as a byproduct in hydrolyzing astragaloside IV with hesperidinase to prepare the aglycone thereof in the process of studying the structure of astragaloside IV, however, no report on the pharmacological effects thereof was found in the literature. Our studies reveal that CMG has similar cardiovascular pharmacological activity just as astragaloside IV (see Examples of this application), whereas the solubility thereof is better than that of to astragaloside IV and other known cycloastragenol compounds, so that it is more feasible for CMG to be developed as a medicine. Published invention patent application (international application number: PCT/US2004/020277, Chinese patent application publication number: CN1809364A) describes a method of preparing CMG by hydrolyzing astragaloside IV with a mild acid, wherein the main product actually obtained from the reaction is cycloastragenol (52%) and the yield of CMG is very low (21%); and moreover, due to interference of other byproducts, purification by means of a separation method such as Silica Gel Column Chromatography is needed to get a pure product, which is unsuitable for commercial mass production.
